Coating treatments using coating agents are performed on various base materials such as metal bodies of automobiles, metal materials for pre-coating, plastic housings for home electric appliances of mobile phones and personal computers, building materials etc in order to improve the appearance and to protect the surface thereof. When such coating agents are used for coating treatments, small amounts of surface conditioners known as smoothing agents such as leveling agents or cissing-preventing agents are pre-blended in the coating agents to prevent the generation of cissing caused by crawling due to the insufficient wetting property of the coating agents and also to prevent the generation of cratering on the surface of the coating layer, so that the coating layer becomes smooth.
As such surface conditioners, silicone-type surface conditioners including polyether-modified polydimethylsiloxanes or polymer-type surface conditioners including polymers formed by polymerization of unsaturated monomers such as (meth)acrylic acid esters and vinyl ethers are used. The coating agent blended with the silicone-type surface conditioner shows an excellent base material-wetting property resulted from its low surface tension which is attributed to the silicone structure thereof, and the surface of a coating layer to which the coating agent is applied shows an excellent leveling property. However, due to the low surface tension, the adhesion of the over-coating is disturbed. Moreover, when baking-finish-coating is performed, the surface conditioner is thermally decomposed due to the insufficient heat resistance attributed to the polyether structure thereof, and thus cissing or protruded humps may be generated by contraries.
On the other hand, the coating agent blended with the polymer-type surface conditioner does not disturb the adhesion of the over-coating and shows the high heat resistance because the surface conditioner has good compatibility in the coating agent attributed to the polymer structure between unsaturated groups. However, the surface tension thereof is not as low as the surface tension attributed to the silicone structure, so the base material-wetting property is insufficient. Also, due to contamination of foreign matters such as dusts or impurities such as oil dusts, the cissing-preventing property is insufficient and causes the generation of the cissing. Therefore, such surface conditioner is required to use accordingly depending on the respect for the purpose or usage of the leveling property, the cissing-preventing property, the heat resistance etc.
As a surface conditioner with an improved leveling property, a cissing-preventing property and a heat resistance, the Japanese Patent Publication 2002-241698 A discloses a smoothing agent for paint and ink which comprises a copolymer of silicone oil having a silicone structure and (meth)acrylic acid ester having a polyether structure. However, a further surface conditioner of general use that decreases the above-mentioned problems while further improving the leveling property, the cissing-preventing property, the heat resistance, the base material-wetting property and the adhesion property of the over-coating are desired.
The present invention is developed to solve the above-mentioned problems. It is an object of the present invention to provide a surface conditioner for a coating agent. The surface agent, which is blended in the coating agent in small amounts, can impart a base material-wetting property and a cissing-preventing property to the coating agent when blended in the coating agent, can impart a leveling property to the coating layer which the coating agent is applied to form a coating layer so as to improve the appearance and smoothness of the surface thereof, can improve an adhesion property of over-coating, can impart an excellent leveling property with heat resistance to the coating agent when blended in a baking paint which is cured at a high temperature. It is another object of the present invention to provide a coating agent to which said surface conditioner is blended.
The surface conditioner for the coating agent of the present invention developed to solve the above-mentioned objects comprises:
a copolymer composed of 1 to 40 parts by weight of an acrylate monomer (A) having a siloxy group, 2 to 80 parts by weight of an N-vinyllactam monomer (8), and 10 to 97 parts by weight of an alkyl(meth)acrylate monomer (C) of which an alkyl group has 1 to 12 carbon atoms;
and weight average molecular weight of the copolymer is 1000 to 120000.
In the surface conditioner for the coating agent, the acrylate monomer (A) having the siloxy group is selected from the group consisting of;
at most 40 parts by weight of a mono(meth)acrylate with (meth)acrylic modification at one terminal, which is represented by the following chemical formula (I)
in the chemical formula (I), R1 is a hydrogen atom or a methyl group, R2 is an alkylene group having 1 to 10 carbon atoms, R3 is an alkyl group having 1 to 12 carbon atoms, and m is a positive number of 2 to 150,
at most 40 parts by weight of a mono(meth)acrylate with (meth)acrylic modification at one terminal, which is represented by the following chemical formula (II)
in the chemical formula (II), R4 is a hydrogen atom or a methyl group, R5 is an alkylene group having 1 to 10 carbon atoms,
and/or 1 to 10 parts by weight of a di(meth)acrylate with (meth)acrylic modification at both terminals, which is represented by the following chemical formula (III)
in the chemical formula (III), R6 and R9 is a hydrogen atom or a methyl group, R7 and R8 are an alkylene group having 1 to 10 carbon atoms, n is a positive number of 2 to 150;and the N-vinyllactam monomer (B) is N-vinyl-2-pyrolidone and/or N-vinyl-ε-caprolactam.
In the surface conditioner for the coating agent, the copolymer is composed of the acrylate monomer (A) having the siloxy group, the N-vinyllactam monomer (B), the alkyl(meth)acrylate monomer (C), and (meth)acrylate monomer (D) with lactone-modification,
and a ratio by weight of the monomers (A) to (C) and the monomer (D) is 100:1 to 100:90,
In the surface conditioner for the coating agent, the copolymer has a property, which a rising temperature beyond 10% of weight reduction of the copolymer is ranging from 280 to 400° C.
A base material-wetting agent of the present invention comprises; the surface conditioner for the coating agent.
A leveling agent of the present invention comprises; the surface conditioner for the coating agent.
A coating agent of the present invention comprises; the surface conditioner for the coating agent, and coating ingredients.
A coating layer of the present invention comprises; the coating agent. And the coating agent is applied and then dried or cured.
The surface conditioner for the coating agent of the present invention has general versatility since it can be blended in an aqueous or non-aqueous coating agent. The surface conditioner for the coating agent can impart a wetting property for a base material to the coating agent when the coating agent blended with the surface conditioner is applied to the base material, and therefore, an excellent leveling property can be given to the surface of the coating layer. The surface conditioner for the coating agent acts as the base material-wetting agent or the leveling agent.
The base material-wetting agent of the present invention prevents generation of cissing caused by pollution of foreign matters such as grits and dusts or contamination of oil dusts when applying the coating agent including the base material-wetting agent, and also prevents generation of pinholes on the surface of the coating layer after applying thereof.
The leveling agent of the present invention can make the surface of the coating layer formed by applying the coating agent including the leveling agent smooth and can make the thickness of the coating layer even while prevents generation of unevenness of the coating, cratering, humps and orange peel with irregularity on the surface of the coating layer. Therefore the leveling agent adjusts the surface to be flat.
The coating agent of the present invention can express an excellent leveling property to the surface of the coating layer formed by applying the agent, even when over-coating is performed on the surface of the coating layer at a room temperature and then heated if necessary, or a baking-finish-coating treatment is performed to the coating layer at 250° C.
The coating layer of the present invention has fine and smooth appearance. Moreover, the coating layer does not cause unevenness of over-coating when the coating layer is finish-coated. The coating layer accomplishes sufficient adhesion to the over-coating layer, and thus they are tightly adhered together. Both coating layer and over-coating layers do not peel off so as to achieve aesthetic appearance and excellent durability.
The coating layer has sufficient heat resistance even when a baking treatment after coating of a coating agent for pre-coating metal is performed at high temperature. Therefore, cissing and humps are not generated on the surface of the coating layer while leveling property is sufficient and the adhesion property of the over-coating is not obstructed.
Hereunder, the embodiments of the present invention will be explained below in detail, but the scope of the present invention is not limited thereto.
The surface conditioner for the coating agent of the present invention comprises the copolymer composed of 1 to 40 parts by weight of the acrylate monomer (A) having the siloxy group, 2 to 80 parts by weight of the N-vinyllactam monomer (B), and 10 to 97 parts by weight of the alkyl(meth)acrylate monomer (C) of which the alkyl group has 1 to 12 carbon atoms.
If the acrylate monomer having the siloxy group (A) is less than 1 part by weight, the base material-wetting property and the cissing-preventing property of the coating agent are not imparted to the coating agent sufficiently. On the other hand, if the acrylate monomer having the siloxy group (A) is more than 40 parts by weight, the compatibility with the ingredients in the coating agent such as resin becomes extremely insufficient. As a result, not only the leveling property becomes insufficient, but also the cissing or cratering is generated on the surface of the coating layer when the coating agent comprising thus acrylate monomer is applied. Moreover, the leveling property of the over-coating deteriorates resu Its the insufficient adhesion property of the over-coating.
If the N-vinyllactam monomer (B) is less than 2 parts by weight, the sufficient leveling property can be obtained but the sufficient base material-wetting property and cissing-preventing property cannot be obtained. On the other hand, if the N-vinyllactam monomer (B) is more than 80 parts by weight, the leveling property becomes insufficient.
If the alkyl(meth)acrylate monomer (C) is less than 10 parts by weight, sufficient leveling property cannot be obtained. On the other hand, if the alkyl(meth)acrylate monomer (C) is more than 97 parts by weight, the base material-wetting property and the cissing-preventing property cannot be obtained.
It is preferable that 2 to 20 parts by weight of the acrylate monomer having the siloxy group (A), 4 to 40 parts by weight of the N-vinyllactam monomer (B) and 20 to 80 parts by weight of the alkyl(meth)acrylate monomer (C) are copolymerized in this range.
The weight-average molecular weight of the copolymer is within the range of 1000 to 120000. If the weight-average molecular weight is less than 1000, the spume of the coating agent is compounded furiously. On the other hand, if the weight-average molecular weight thereof is over 120000, the compatibility thereof with ingredients in the coating agent such as resin deteriorates excessively to get the coating agent cloudy or to generate cratering on the surface of the coating layer to which the coating agent comprising thus copolymer is applied. It is preferable that the weight-average molecular weight of the copolymer is within the range of 2000 to 60000.
The acrylate monomer (A) having the siloxy group is exemplified by the mono(meth)acrylate with (meth)acrylic modification at one terminal represented by the following chemical formulas (I) or (II).
The chemical formula (I) is represented by
wherein R1 is a hydrogen atom or a methyl group, R2 is an alkylene group having 1 to 10 carbon atoms, and m is a positive number of 2 to 150.
The chemical formula (II) is represented by
wherein R4 is a hydrogen atom or a methyl group and R5 is an alkylene group having 1 to 10 carbon atoms.
Examples of the acrylate monomer (A) having the siloxy group represented by the chemical formula (I) or (II) are Silaplane FM-0711, Silaplane FM-0721, Silaplane FM-0725, Silaplane TM-0701 and Silaplane TM-0701T which are available from Chisso Corporation (“Silaplane” is a trademark of Chisso Corporation), and X-22-174DX, X-22-2426 and X-22-2475 which are available from Shin-Etsu Chemical Co., Ltd.
The acrylate monomer (A) having the siloxy group constructing the copolymer is preferably used at most 40 parts by weight of at least one of the group consisting of monomers represented by the chemical formulas (I) and (II). However, it can be a monomer represented by at least either chemical formula (I) or (II) and a di(meth)acrylate with (meth)acrylic modification at both terminals represented by the following chemical formula (III)
wherein R6 and R9 are the same or different each other, a hydrogen atom or a methyl group, R7 and R8 are the same or different each other, an alkylene group having 1 to 10 carbon atoms, and n is a positive number of 2 to 150.
Examples of the di(meth)acrylate are Silaplane FM-7711, Silaplane FM-7721 and Silaplane FM-7725 which are available from Chisso Corporation, and X-22-164, X-22-164AS, X-22-164A, X-22-164B, X-22-1640 and X-22-164E which are available from Shin-Etsu Chemical Co., Ltd.
1-10 parts by weight of the di(meth)acrylate is preferably copolymerized with the acrylate monomer having the siloxy group represented by the chemical formula (I) or (II). If the di(meth)acrylate is more than 10 parts by weight, geling of the copolymer composed thereof could occur.
The N-vinyllactam monomer (B) is a lactam five- to seven-membered ring having a substituent of an N-vinyl group. More specifically, N-vinyl-2-pyrolidone and N-vinyl-ε-caprolactam can be exemplified. These can be used alone or combined.
The alkyl(meth)acrylate monomer (C) means an alkyl acryate or an alkyl methacrylate. Concretely, examples of the alkyl (meth)acrylate monomer (C) are methyl(meth)acrylate, ethyl(meth)acrylate, normal-propyl(meth)acrylate, isopropyl(meth)acrylate, normal-butyl(meth)acrylate, isobutyl(meth)acrylate, tertiary-butyl(meth)acrylate, normal-octyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, isononyl(meth)acrylate, isodecyl(meth)acrylate and dodecyl(meth)acrylate.
The copolymer may be copolymerized from the acrylate monomer (A) having the siloxy group, the N-vinyllactam monomer (B), the alkyl(meth)acrylate monomer (C) and the (meth)acrylate monomer (D) with lactone-modification, of which a ratio by weight of the monomers (A)-(C) and the monomer (D) is 100:10-90. It is preferable that the ratio is 100:5-70.
The copolymer may be copolymerized from the acrylate monomer having the siloxy group (A), the N-vinyllactam monomer (B), the alkyl(meth)acrylate monomer (C), the lactone-modified (meth)acrylate monomer (D) and, besides these, a diluent monomer (E) which can be copolymerized. The diluent monomer (E) is not limited to any species, and it can be copolymerized as long as it does not disturb the surface conditioning effect of the surface conditioner for the coating agent. Specific rate of the diluent monomer (E) by weight is within the range of 40% to the total amount of the acrylate monomer having the siloxy group (A), the N-vinyllactam monomer (B) and the alkyl(meth)acrylate monomer (C).
Examples of the lactone-modified (meth)acrylate monomer (D) are reaction products of an acrylic-type monomer containing a hydroxyl group and a lactone-group compound represented by β-propiolactone, dimethylpropiolactone, butyllactone, γ-valerolactone, γ-caprylolactone, γ-laurylolactone, ε-caprolactone or δ-caprolactone. Concretely, examples of such lactone-modified (meth)acrylate monomer (D) are PLACCEL FM5 (trade name; caprolactone-modified methacrylate hydroxyl esters), PLACCEL FM2D, PLACCEL FM3, PLACCEL F1 DDM, PLACCEL FA2D, PLACCEL FA10L etc., which are available from Daicel Chemical industries, Ltd.
Examples of the diluent monomer (E) are a (meth)acrylic acid monomer such as acrylic acid and methacrylic acid; a (meth)acrylate monomer such as 2-hydroxyethyl(meth)acrylate, stearyl(meth)acrylate and benzyl(meth)acrylate; a (meth)acrylamide monomer such as (meth)acrylamide; an aromatic vinyl monomer such as styrene and vinyl toluene; a straight- or cyclic-alkyl vinyl ether monomer having the alkyl of 1 to 12 carbon atoms such as normal-butyl vinyl ether, isobutyl vinyl ether, dodecyl vinyl ether and cyclohexyl vinyl ether; a vinyl ester monomer such as vinyl acetate, vinyl propionate and vinyl laurate.
Although the heat resistance of the copolymer is depended on the species of the monomer, so as long as each monomers within the range of the ratio by weight, the copolymer has the heat resistance.
The surface conditioner for the coating agent may consist of the copolymer only, or may comprise the copolymer dissolved or suspended in an inactive solvent for the preparation thereof.
It is preferable that the inactive solvent can dissolve or suspend the copolymer and can be admixed in the surface conditioner for the coating agent. Specifically, examples of the inactive solvent are a hydrocarbon-type solvent such as xylene, toluene and cyclohexane; a ketone-type solvent such as cyclohexanone and methyl isobutyl ketone; an ether-type solvent such as methyl cellosolve, cellosolve, butyl cellosolve, methyl carbitol, carbitol, butyl carbitol, diethyl carbitol and propylene glycol monomethyl ether; an ester-type solvent such as normal-butyl acetate, isobutyl acetate, normal-amyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and 3-methoxybutyl acetate, an alcohol-type solvent such as normal-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, cyclohexanol, 2-ethylhexanol and 3-methyl-3-methoxybutanol. These solvents may be used alone or mixed plurally.
The surface conditioner for the coating agent is prepared as follows. The acrylate monomer having the siloxy group (A), the N-vinyllactam monomer (B), the alkyl(meth)acrylate monomer (C), and if necessary the lactone-modified (meth)acrylate monomer (D) and if necessary the diluent monomer (E) are copolymerized through a random copolymerization if necessary in the solvent, under presence of a radical polymerization initiator and if necessary a chain transfer agent, to prepare the surface conditioner for the coating agent.
The surface conditioner for the coating agent may be obtained by mixing the inactive solvent and the copolymer after synthesizing the copolymer.
The method for the copolymerization of the copolymer may be cationic copolymerization or anionic copolymerization.
The copolymer may be a block copolymer or a graft copolymer.
The surface conditioner for the coating agent may be used as a base material wetting agent, a cissing-preventing agent or a leveling agent, while it may be blended in either aqueous coating agent or non-aqueous coating agent. The coating agent blended with the surface conditioner for the coating agent develops excellent base material-wetting property, cissing-preventing property and leveling property, and may further have defoaming property.
When it is used as the base material-wetting agent, the coating agent is able to apply onto the base material with a poor wetting property such as plastics without repelling thereof. It is used for the cissing-preventing agent as well as the base material-wetting agent.
The surface conditioner for the coating agent can be blended in a coating agent for high temperature baking such as a coating agent for pre-coating of metal substrate. The copolymer in the surface conditioner for the coating agent in this case has the following thermal property from the aspect of fundamental heat resistance of the copolymer preferably. As regards to the thermal property, a rising temperature, which the reduced quantity of the heated copolymer through heating from the original copolymer is 10% by weight, is preferably ranging from 280 to 400° C. Hereunder, thus specific rising temperature is termed as “the rising temperature at 10 weight % reduction”.
The rising temperature at 10 weight % reduction is obtained by thermo-gravimetric analysis (TG). The rising temperature at 10 weight % reduction is identified by the temperature when weight of a sample of the copolymer is reduced during heat up beyond 10% through decomposition or sublimation thereof.
If the rising temperature at 10 weight % reduction of the copolymer is less than 280° C., the coating agent for high temperature baking blended with the copolymer such as the coating agent for pre-coating of the metal substrate deteriorates the adhesion property of the over-coating and the base material-wetting property distinctly because, when thus coating agent for high temperature baking is applied onto the material to bake at approximately 250° C., the copolymer decomposes by the heat and then the cissing or humps are generated at the surface of the coating layer due to the decomposing material thereof.
If the rising temperature at 10 weight % reduction of the copolymer is more than 400° C., the compatibility of the copolymer with other ingredients such as the resins in the coating agent deteriorates, so that the coating agent tends to get cloudy or generate dissociation of the copolymer and other ingredient.
The coating agent of the present invention is prepared by pre-mixing the coating ingredients, blending with the surface conditioner for the coating agent, and then kneading thereof. They may be mixed all together, or in arbitrary order.
In the acceptable embodiment, 0.01-20% by weight, preferably 0.1-1.0% by weight as a converted solid content concentration of the surface conditioner for the coating agent may be blended in the coating agent.
The coating ingredients blended in the coating agent are not limited. Examples of the coating ingredients are colorant such as a pigment and a dye; a resin; a diluent solvent; a catalyst; and a surface-active agent. Also, if necessary, a sensitizer, an antistatic agent, a defoaming agent, a dispersant or a viscosity modifier may be blended in the coating agent.
Examples of the resin are an acrylic resin, a polyester resin, an urethane resin, an alkyd resin, an epoxy resin, an amino resin etc. In particular, those resins may be heat-cured-type-, ultraviolet-cured-type-, electron-cured-type-, oxidation-cured-type-, cationic poto-cured-type-, peroxide-cured-type-, and acid/epoxy-cured-type-resins. Thus resins may be prepared by curing under presence or absence of a catalyst with a chemical reaction. Thus resins also may be a resin having high glass-transition point, which simply forms the coating layer by volatilization of the solvent without any chemical reaction.
The diluent solvent is not limited as long as it is an organic solvent of general use. Examples thereof are a hydrocarbon-type solvent such as xylene, toluene and cyclohexane; a ketone-type solvent such as cyclohexanone and methyl isobutyl ketone; an ether-type solvent such as methyl cellosolve, cellosolve, butyl cellosolve, methyl carbitol, carbitol, butyl carbitol, diethyl carbitol and propylene glycol monomethyl ether; an ester-type solvent such as normal-butyl acetate, isobutyl acetate, normal-amyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and 3-methoxybutyl acetate; an alcohol solvent such as normal-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, cyclohexanol, 2-ethylhexanol and 3-methyl-3-methoxybutanol. These solvents may be used alone, mixed plurally, if necessary with further water.
The coating layer of the present invention is prepared by applying the coating agent onto the base material, and then forming the coating from the coating portions by drying or curing at the surface thereof.
Although the base material is not limited, examples of raw material thereof, which forms the base material, are plastics, rubber, paper, wood, glass, metal, stone, cement, mortar and ceramics. Examples of the base material are used for exterior materials of home electric appliances or automobiles, commodities, and architectural materials.
Examples of the coating method of the coating agents are a spin coating method, a slit coating method, a spray coating method, a dip coating method, a bar coating method, a doctor blade method, a roll coating method and a flow coating method.
Preparation Examples 1 to 5 show embodiments of preparing surface conditioners for a coating agent of the present invention, and Comparative Preparation Examples 1 to 5 show embodiments of preparing surface conditioners which are outside of the scope of the present invention.